A silver halide color photographic material has, in general, three kinds of silver halide emulsion layers which are different in color sensitivity. Color images are reproduced by the so-called subtractive color process, or the method of developing yellow, magenta and cyan colors of color couplers (abbreviated as "couplers") incorporated in the emulsion layers. The color images obtained by subjecting such a silver halide color photographic material to development-processing generally consist of azomethine dyes or indoaniline dyes produced by the reaction of couplers with the oxidation product of an aromatic primary amine developing agent. To ensure satisfactory color reproducibility, intensive research has been done on couplers which can form clear dyes having reduced side absorption.
In silver halide color photographic materials as described above, phenol or naphthol derivatives have hitherto been used as prevalent cyan dye-forming couplers (abbreviated as "cyan coupler", hereinafter). However, the dyes formed from these couplers have undesirable absorption in blue and green regions, so that considerable deterioration in color reproducibility is a serious problem of said couplers. With the intention of overcoming the weaknesses of conventionally used couplers, the following ones are proposed.
For instance, 2,4-diphenylimidazoles are disclosed in EP 0 249 453 A2. Since the dyes formed from those couplers are weak in undesirable absorption on the shorter wavelength side, compared with dyes formed from conventional couplers, they are in the direction desirable for color reproduction. However, the color reproducibility of such couplers is not highly satisfactory, and they still have problems in practical use, such as their coupling activities are low, their fastness to heat and light are considerably low, and so on.
Pyrazoloazoles are disclosed in JP-A-64-552 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-64-553, JP-A-64-554, JP-A-64-555, JP-A-64-556 and JP-A-64-557. Although the dyes formed from those couplers are reduced in absorption in the shorter wavelength side, compared with conventional dyes, the extent of the reduction is not sufficient for color reproduction. In addition, such compounds do not have sufficient color formability as cyan couplers, so that a practical problem exists.
The present inventors have already proposed pyrroloazoles as another type of cyan dye-forming couplers with mitigated drawbacks. Specifically, the cyan couplers of pyrroloazole type are high in coupling activity, and are remarkably improved over conventional ones with respect to the absorption characteristic on the shorter wavelength side, such that production of such dyes is highly desirable for color reproduction. In addition, the dyes formed from the couplers of this type have higher extinction coefficients than those formed from conventional couplers, so that these couplers are superior because they provide an intended density of developed color at a smaller coverage than conventional couplers. However, the fastness, particularly to light, of such dyes in photosensitive materials is still unsatisfactory in a practical sense. (Making an additional remark, the couplers containing 1H-pyrrolo[1,2-b][1,2,4]triazole as a mother nucleus are described in the notes of lectures at the annual convention of Japanese Photographic Society in the 60th year of Showa (held on May 23 and 24 in 1985, at Shigaku Kaikan), pages 108-110, and disclosed in JP-A-62-279339 and JP-A- 62-278552. However, those couplers are known as magenta couplers, and the dyes produced therefrom have their absorption maxima in the green region although they have slight side absorption.)
The above-described problems of fading and discoloration of color images are of great importance in color photosensitive materials used for artistic purposes. It has been proposed to use discoloration inhibitors to solve the fading and discoloration problems, ultraviolet absorbents for the purpose of preventing deterioration in image quality caused by ultraviolet rays, and so on.
As known inhibitors described above, there are hydroquinones, hindered phenols, catechols, gallic acid esters, aminophenols, hindered amines, chromanols, indanes, the ethers or esters obtained by silylating, acylating or alkylating the phenolic OH group in each of the above-cited compounds, metal complex salts and so on.
However, those compounds are still insufficient in effects, although their effects as inhibitors against the fading and discoloration of color images are appreciable. In addition, some of them cause a change in hue, generate fog, are poor in dispersibility, or deposit microcrystals after the coating of emulsions. Therefore, color photographs with excellent comprehensive properties cannot yet be ensured by the use of discoloration inhibitors alone.
It was found that when a multilayer color photosensitive material was designed so as to arrange the silver halide emulsion layer containing a pyrroloazole type cyan coupler in the position farthest from the support, said cyan couplers have a problem of the maximal densities of colors developed in the silver halide emulsion layers containing magenta and yellow couplers respectively, which are present nearer to the support than the foregoing cyan coupler containing emulsion layer, are lower than those obtained by the use of conventional cyan couplers.
Therefore, it has been desired to make further improvements upon the silver halide color photographic materials containing couplers of the above-described type which meet recent demands for high standards of processability, color formability, fastness and so on.